Well, for now, removing that nowrap attribute will fix the immediate problem with content width.
At time of writing, the page is showing a 404 as the URL points to mission_intro.php rather than mission_intro.html
I'm sure other Sitepoint regulars will have plenty of good ideas for how best to adapt your workflow to CSS layouts. Perhaps ask for help in converting a single page to begin with. There are some keen and fast workers around here.
An important point is not to allow Photoshop to dictate the markup, which tends to result in inflexibility. For instance, increasing the font size in my browser causes gaps to appear in your Home page, resulting in purple text on a purple background. Photoshop is a great tool as long as it is wielded with an understanding of how to combine graphics with sound markup. Let visual design work for content, rather than content being constrained by design.
Once you've grasped the principals of CSS layout, and applied them, you will wonder how you ever managed with tables, especially in such deep nesting.